The existing secondary battery generally comprises an electrode assembly, a case and a cap plate, the electrode assembly is received in the case, the cap plate is assembled with the case, and an electrode tab of the electrode assembly is electrically connected with an electrode terminal provided on the cap plate. In order to ensure a connection strength between the electrode tab and the electrode terminal, the electrode tab needs to have a sufficient large length, and a protecting piece needs to be provided below the electrode tab; in order to reduce the space occupied by the electrode tab, the electrode tab needs to be bent to two layers along an end portion of the protecting piece, which will lead to a contact between the electrode tab and the end portion of the protecting piece; because the electrode tab is thin and a burr is generated in the end portion of the protecting piece during stamping process of the protecting piece, in the production process and the working process of the secondary battery, the electrode tab will be easily pierced by the burr in the end portion of the protecting piece when the secondary battery is dropped, which leads to short circuit of the electrode assembly or circuit interruption of the electrode assembly, and decreases the safety performance of the secondary battery.